And it's not as obvious as clicking an "invite friends" button to invite them directly. Google opened up that possibility last night but then shut it down after a fleeting moment because of what Google's Vic Gundotra called "insane demand."

Instead, you have to use a built-in e-mail option for Google+ that happens to have a viral marketing component. Here are the steps.

First, figure out who you'll send invitations to. If they're already in your Gmail address book or another Google service, you're a step ahead. If not, there's some cutting and pasting in your future.

For friends whose e-mails are already in your Gmail address book or otherwise discoverable in Google+'s Circles section, add them to a special circle you created for G+ invitees. If they're not in your contacts, just hold onto their addresses for now.

Next, start a new Google+ message, the equivalent of a Facebook update message or a Twitter tweet. In it, type an invitation message with an expectations-lowering caution. Here's what I've been saying: "This message serves as an invite to Google+. Google throttles the signup rate, though, so it may not work at first. If not, try again later."

A look at the way to invite people to Google+ without a direct invitation option.
Screenshot by Stephen Shankland/CNET

Next, address the message. Clear out any existing circles, then add your Google+ invitee circle. If you have individual e-mail addresses, now's the time for pasting: click on the "+Add more people" words below the message box and paste in the addresses. You'll have to click on each one to register it as you go.

Last, click the "share" button. That's it!

Editor's note: Google has been opening and closing invitations over the last few days, so some users are getting messages that say Google has hit its invite cap. If you get that message, just try again later.

About the author

Stephen Shankland has been a reporter at CNET since 1998 and covers browsers, Web development, digital photography and new technology. In the past he has been CNET's beat reporter for Google, Yahoo, Linux, open-source software, servers and supercomputers. He has a soft spot in his heart for standards groups and I/O interfaces.
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